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[Support] Replace deprecated std::aligned_union, NFCI. #127417

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Merged
merged 1 commit into from
Feb 25, 2025
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[Support] Replace deprecated std::aligned_union, NFCI. #127417

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10 changes: 2 additions & 8 deletions llvm/include/llvm/Support/AlignOf.h
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Original file line number Diff line number Diff line change
Expand Up @@ -13,20 +13,14 @@
#ifndef LLVM_SUPPORT_ALIGNOF_H
#define LLVM_SUPPORT_ALIGNOF_H

#include <type_traits>
#include <algorithm>

namespace llvm {

/// A suitably aligned and sized character array member which can hold elements
/// of any type.
///
/// This template is equivalent to std::aligned_union_t<1, ...>, but we cannot
/// use it due to a bug in the MSVC x86 compiler:
/// https://github.com/microsoft/STL/issues/1533
/// Using `alignas` here works around the bug.
template <typename T, typename... Ts> struct AlignedCharArrayUnion {
using AlignedUnion = std::aligned_union_t<1, T, Ts...>;
alignas(alignof(AlignedUnion)) char buffer[sizeof(AlignedUnion)];
alignas(T) alignas(Ts...) char buffer[std::max({sizeof(T), sizeof(Ts)...})];
};

} // end namespace llvm
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